In theory, if you "cleaned" your surface perfectly, you would remove ALL of the microbes and any potential food for microbes to live, grow or breed upon. Then you would not need to sanitize. In the real world perfection doesn't happen. Since none of these surfaces are sterile. The best we do is to reduce the numbers of the "bad" microbes and hope the "good" ones out-compete them.
Still, it is my belief that good hygiene is more important than your sanitizer choice. Any microbe (yeast, mold, virus or bacteria) that gets washed away, won't need to be killed. There was lots of "good" beer produced in the 19th century when there was no sanitizer use and hygiene was the only control method.
After good cleaning, as a regular practice I use both solutions of StarSan (in a spray bottle on stainless fermenter), and bleach (buckets, tubing, & siphon, small equipment), so for me it is a matter of which is most convenient for a given piece of equipment.
Still, if I thought I had an infected piece of equipment it'd go to the bleach, maybe with a boiling water chaser if appropriate.